As expected, Nokia has just announced that it has started the rollout of the hotly-anticipated Windows Phone 8 update for Lumia 920 and 820.

Codenamed Portico, the software update is now pushed OTA (over the air) in the United States and Canada. Rogers and AT&T customers who own one of the two devices will be notified on the update any moment now.

According to Nokia, the Windows Phone 8 update brings the following changes:

- Enhancements in Messaging;

- More efficient and reliable Bluetooth connectivity;

- More efficient and reliable start-up sequence;

- Enhancements in imaging performance and battery management;

- Additional platform updates and enhancements.

Unfortunately, the Finnish company stated that the update would be available for Lumia 920 and Lumia 820 owners in other regions in early 2013. Stay tuned for more info on the matter.